cbeighton



E. E. F. CREIGHTON.

ELECTRICAL APPARATUS.

APPLICATION mio una. 191s.

1,317,002. l Y! .70 Pmfedsept. 23,1919.

inventor Elmer 1i. Ff Creighton,

bg Jogy-k;

His qttor'eg.

. Y. l( UNITED STATES PATENT 'OFFICE.

m E. F. CBEIGHTON, 0F 'SCHENECTADY,`NEWYOBK, ASSIGNOB TO GENERAL ELECTRIC COMPANY, CORPORATION 0F NEW YORK.

ELECTRICAL APPARATUS.

To all whom it may concern.'

Be it known that I, ELMER E. F. Canica- 'roN, a citizen of the UnitedStates, residing at Schenectady, in the county 0f Schenectady, State of New York, have invented certain new and useful Im rovements in Electrical Ap aratus, of which the followin is a speci cation.

n its broad aspect mypinvention is applicable to various types of nelectrical apparatus; it relates particularly, however, to reactors and is of peculiar interest to other electrical apparatus comprising windings. My invention has a number of objects. One object is to protect electrical .apparatus against the effects of excessive voltages, p articularly against the gradual building up or development of such voltages as b resonance and transient phenomena o steep wave fronts. Still another object is the absorption or dissipation of abnormally high frequency energy and the energy of tran' sients of steep wave fronts. My invention may be embodied in various types of working apparatus for the accomplishment of these objects in such apparatus directly, or it may be embodied in apparatus which is esssentially protective in its nature and ein ployed for the protection of other apparatus. In this latter aspect my invention contem- 'plates the provision of a high frequency absorber and also an improved reactor of sim le and cheap construction embodying in it t e characteristics of a high frequency absorber.

A reactor for wer or current limitation embodying my mvention is illustrative of the general nature and application of my invention. In carrying out the objects of my invention, I cause th reactor to consume. absorb, or dissipate energy of excessive voltages, and to' this end I preferably. provide for the distributed leakage of current -between turns of the reactor, as by distributing electrical energy consuming paths between the turns. The resistance of these consuming paths is so high that, .fat least under normal differences of potential between turns, littleleakage occurs under normal conditions, and hence little energy is lost during normal operation. Under excessive differences of potential between turns, however, such as those caused by resonance, or by surges or traveling waves of steep wave normal fronts when encountering the inductance of the device, or under excessive'potentials produced in any other way, the leakage between turns is-increased to such values as to sipate appreciable energy of the excessive voltages, and hence of the abnormal frequencies orother factors which may have caused those voltages. By more or less thoroughly dlstributmg the energy consuming or leakage paths throu hout the winding rather than disposing tgeni at a very few points, protection is secured not o'nly against excess potentials appearing'at-the terminals ofthe apparatus but also against local or internal excess potentials as those resulting from internal resonance and surges and such as may V:not apiear at the connection points l of concentrate resistance. The applicat' n of leakage paths to various-apparatxis take a numberof forms, de nding upon the considerationsencountered);e some of these forins are later described in some detail. From another aspect in invention, both as applied to reactors an to other electrical apparatus, comprises the use of semi-conducting material between turns in more or distributed masses, the semi-conducting material acting substantially as an insulator under normal conditions and potentials but 'passing sutiicient current under excessive potentials,'such as potentials built up by danrously excessive frequencies, to relieve the angerous stresses or prevent the appearance of the stresses in dangerous values. The nature of the semi-conducting material is more particularly described hereinafter.

A reactores thus provided with leakage paths in addition to its functions as a current limiter strictly at normal frequencies,

' einem umarmen. Patented sepaea, 1919.

absorber which need not necessarily possess the abilit to limit' the current materially at uencies as does a: reactor. A high frequency absorber according to my invention need possess merely suticient inductance to build up the voltages of the abnormal frequencies, travelin waves, or other transients, to some excessive value; the inductance being shunted by leakage paths for absorbing appreciable ener atsuch value of voltage, the leaka pat s being preferably distrbuted an preferably provided by semi-conducting material between adjacent turns or other sections of the device. Such absorbers may, for example, be distributed alongl a transmission line, since their impedance values at normal frequencies may be so low that they have substantially no eect on the normal energy iiow.

While my invention is, then, particularly agpllcable to reactors and high frequency a sorbers, it is also apphcable to other apparatus for the direct protection thereof, peculiarly to such apparatust as comprise windings, leakage paths being provided as in reactors between conducting portions of the parts of the apparatus to b e protected. In some other electrical windings there is more likelihood of developingdangerously excessive potentials by-resonarce and transients generally, especially internally or locally; than in windings of reactors. In such apparatus it is rticularly desirable to more or less thorougilidy age paths throughout the same for/protection especially against the abnormal interna-l or local voltages offresonance. Providing Y working apparatus with such means for seable in some cases.

generally be very intimate to secure the best curing its own protection tends to the elimination of apparatus which is entirely protective in its functions.

The semi-conducting material preferably is of such high resistance under normal conditions as to be substantially an insulator;

on the other hand, under excessive potentials which are too low4 to be dangerous to the apparatus, it must pass sufiicient'current to dissipate, absorb, or consume appreciable energy. Suitable materials may be found in mixtures of insulating materials and conducting materials. A mixture of an insulating material and a very high resistance conducting material seems preferable, although a mixture of an insulating material "and a low resistance conducting material is suit- The mixture should results as uniformity and stability, and to this end the constituent materials in some cases, if in solid states, should be finely divided. The proportions of the two kinds of material will vary with the conditions, as the thickness of the masses between the conductin parts of the apparatus to which it is applic the otentials to which such masses are to be su of the materials themselves. Preferably, the semi-conducting material will ssess a negative ampere-volt characteristic; that is, its resistance will decrease as the volta e or power applied to it increases (preferab y independentlyv of the temperature). Carborundum gives this effect. I have oun a mixture of Portlang @ment and finely di vided etro cum co e 1n s stantiall the propor ions o m one to-two parts o coke to one part of cement., measurement by voldistribute the leakduring semi-conducting, n ing parts. Each sectlon comprises an inner j appears carried 'directly j ected, and the characteristics' ume, to very well suit the conditions usually met in the construction of reactors and other high frequency absorbers. The mixture ma be impregnated with a suitable water- 1n material to prevent the a sorp ion of moisture.

. Since as before indicated, my invention is particularly applicable to power or current limiting reactors, and such reactors embodying my invention are illustrative of the neral nature and application thereof, I s all forthe most part illustrate and describe in detail only the application of my invention to reactors. Its application to other electrical apparatus will be understood therefrom. Referring now to the accompanying drawing: Figure 1 is an elevation of a reactor embodymg m invention. Fig. 2 is a plan view of one o the sections thereo'f. Fig. 3 is a sectional view of the section of Fig. 2 on the line 3 3. Figs. 4 and 5 are sectional views on the line 4-5 of a section like that of Fig. 2 illustrating different constructions of the same. Figs. 6, 7 and 8 are crosssections substantially on the line 4-5 of Fig. 2 of one-half of a reactor like that of Fig. 1y illustrating different constructions thereof. Figs. 9 and 10 illustrate other applications of my invention. j

-In the reactor illustrated the conductors 15 are substantially bare, that is, without insulaJtion. The reactor comprises a lurality of horizontal sections like that o Fig. 2, each section containing one layer or coll of the conductor. The conductor of each coil or layer is Wound up on a removable form the construction of the device, the layer orcoil being disposed at an angle to While the conductor or conductors are thus held in place, a plastic 16, some of it at least is cast about the conduct- 17-and outer ring 18 joined by a plurahty of radial supports or arms 19. As from. the figure the conductor is in these supports 19. A (see Figs. 2 and 3) between e inner ring 17 and the bottom of the section and a corresponding space 23 is left between the ring 18 and the top of the section. So many of the sections asy may be necessary in a panticular case are assembled together as illustrated in Fig. 1 to compose the complete reactor, thc coils being interconnected at the inside and outside o the reactor al ternately. Preferably the, sections are alternately reversed (see Fig. 6) so that the inner layers are alternately disposed at opposite angles to the winding case; in this way turns between which greater differences of potential exist are spaced farther apart than turns between which the diierence of potential is of less value. The sections are' assembled with the arms 19 of each section space 22 is left t and the semi-conductor thereof (laici-fre' ferred to) from ground, except, of course, as the conductor or conductors of the' rev actor may be connected to ground in 4.some

instances. 1 y As before indicated, the lastic, or atleast so much of it as is disp between some of the turns Aof the device is of a semi-conducting nature. l'Also as before indicated, this semi-conducting plastic may becomposed of from one to'tvvo parts of very finely divided petroleum coke to one part of Portland cement, the Ymeasurement being by volume, suilicient water being added to makefthe Y mass sufficiently fluid to be readily applied.

` shaped sections and 31 adjacent coils, as t The entire plastic mass may'be composed of this semi-conducting material as is indicated inFi .4. However, for purposes'of economy or ot erwise", a part of the total mass may be composed of some other material, lpreferably a plastic, which may even be non-conducting as illustrated in Fig. Here the wedgeare composed of the part 32 disinsulating 'material, only posed adjacent the turns being semi-conducti' in This construction may be used when the -vo tage between o posite end turns of. two e turns 34 and 35 ofF ig.

' 6, is likely to be higher than should be imressed upon the semi-conducting vmaterial the parts 30 and 31 being dielectric strength to wlthstand the voltage between sc ch turns as 34 ,jl were the whole reactor of the semi-coiiduct f A' ing material. Under the same conditibns or 5' for the same purposes the modilicationillus- A Y y pf .the Sorg used and of the niiclmess Q'f they distance between these turns, the material of of sufficiently -high and 35 and between i-the tui'nsyVj respectively adjacent thereto. lUsing such a construction a reactonmay have smaller dimensions in some cases' lthan trated in Fig. '6 may 'be employed. I'Here only the alternate sections 36 are composed of semi-conducting material, the remaining sections 37 alternating therewith being com- A' posed of an insulatinglmaterial of the requi- .0

site dielectric strengt I have found that vwhere only alternate coils are composed of semi-conducting material the device is quite generally sufliciently protective.

The provision of leakage paths for excessive potential di'erences between turns provide suitable leakage paths between the end turns of electrical windings or between the turns of the terminal coils. A reactor rovided with leakage paths does not reflect ack a. disturbance coming to it to the extent of reactors with thoroughly insulated turns nor does it, pass on out at the opposite apparatus to which l is especially advantageous therefore to i -terminal as much of the energy of a dsturbance which succeeds in entering the reactor as a thoroughly insulated reactor, butv a reactor with lea a'ge paths takes a material part of the energy of the disturbance into itself, dissipates a considerable part of the energy entering it and passes on but a little part of this enterin ener These actions may be modified, eit er inl uced or repressed, by giving the leakage aths proper values of resistance, as by ing the resistance of the leakage paths. rading of the resistance may be carried' out in a number of was. When the semi-conducting material isa mlxture such'as before mentioned, the differ-i ences in theresistances of the leakage 'paths in different arts'of the device will robably genera y be brought about by dli'erences in the proportions of the materials composing the mixtures. Since, however, differences in the constitution of the semiioo conducting material 'are diilicuit to illustrate,

I have chosen to illustrate glrading by differences in the thicknesses oft e layers of semiconducting material in the diierent sections, each of these sections as a whole resembling the section illustrated -in Fig. 5, that is, cmposed of masses of insulating material between which ala er of semi-conducting inaterial is dispose In Fi 7 the semi-conducting material 32 of t e sections 41 at the opposite ends of the, reactor is of considerable depth and hence of low resistance between turns; of the sections 42 adjcent' thereto, of a less depth and somewhat higher 'resistance between turns;'of the sections 43 adjacent to the sections 42 of a still smaller depth and still higher resistance, and of the section 44 at the middle of the reactor of l lthe least depth and highest resistance between turns. In short, the resistances 'of the leakage -paths between adjacent turns are of the lowest values adjacent the ends of actor, reaching their-greatest values at the center thereof. A reactor with such graded leakage paths readily takes into itself a considerable-portion of a disturbance reaching it from either end, and hence receives an ,the reactor and gradually increase in value from both ends toward the center of the redissipates or absorbs a considerable part of 're'sistances of the leakage the energy of the disturbance, and refiects .backQward the source of the disturbance a smaller partof the energy of the disturbance than a thoroughly insulated reactor. In Fig. 8 is illustrated a reactor in which the aths .are so graded that a greater part of t e disturbance (coming from either side) is reected back toward its source than is the case with the reactor of Fig. 7 but the energy of the disturbance which succeeds in enterin the reactor is more and more readily dissipated as it proceeds toward the center of the reactor and hence less is passed on through the reactor to the circuit at the side opposite in which I have contemplated applying that principle so far as it relates to reactors, I have shown and described a reactor coinprising a mass of plastic for supporting and holding the turns of the reactor in position. This matter is not claimed in the present application but is shown and 'described and also claimed in my co-pendin application Serial No. 100,553 led on or a out May 29, 1916. Obviously niy present invention is not limited to such a construction and altogether my invention is subject to many modifications. Other modifications will occur to those skilled in this art and I aim in the appended claims to cover all modifications which do not involve a departure from that on which the disturbance originate the spirit and scopeof my invention.

In the reactor of Fig. 8 the leakage paths adjacent the two terminals are of the highest resistances, and the resistance graduall decreases in value from both ends toward the center. In grading the resistance between turns of a reactor the direction of gradin will depend upon the use of the reactor. I for example, the reactor is to be used between a highly insulated line and a transformer it will at times be desirable to reflect as niuch as possible of the travelin wave back onto the line again and have al that enters the reactor as fully absorbed as possible. Any surge which enters the reactor will have its wave front gradually attened as it progresses through the coil. Therefore in this case. there should be a high resistance between the turns at the line terminal of the reactor and the resistance should decrease in value from this terminal toward the other end of the coil. If, on the contrary, the reactor is for use between transformers where it is undesirable to reect surges which emanate in the transformers back into the transformers, the grading of the resistance should be as illustrated in Fig. 7, that is to say, the lower resistanoes should be `at the end turns and the higher resistances near the center turns. My invention may be applied to other electrical windings than reactors as hereinbefore indicated. It may also be applied in other fashions than those hereinbefore described. In Fig. 9 I have illustrated a coiledl conductor 50 between turns of which is disposed the semi-conducting material 51; in

What I claim as new and desire to secure y Letters Patent of the United States, is:

1. Electrical apparatus for absorbing high frequency energy comprising a conductor and semi-conducting material distributed in electrical contact with said conductor and of a character to pass appreciable current between points on said conductor only when subjected to abnormal differences of po tential. 2. Electrical apparatus for absorbing high frequency energy comprising a conductor and a semi-conductin material distributed in electrical contact with said conductor, arranged to support said conductor and of a character to insulate the same when subjected to normal differences of potential but passing current between points on said conductor when subjected to abnormal differences of potential.

3. Electrical apparatus for absorbing high ifrequency energy comprising a coiled conductor and a semi-conductor between turns thereof, said semi-conductor being of a character substantially to insulate said turns from each other under normal differences of potential between said turns and to pass appreciable current between said turns under excessive differences of potential between said turns.

4. Electrical apparatus for absorbing high frequency energy comprising a coiled conductor and semi-conducting material in distributed electrical connection with the same, said semi-conducting material being of a character substantially to insulate the turns this. case the semi-conducting material 51 'of said conductor from each other under doesnot extend entirely about the conductor normal differences of potential between said (as in the preceding figures) but is as thor- -turns and to pass appreciable current bef oughly distributed as possible through the coil. In Fig. 10 I have illustrated a socalled disk coil, the conductors 55 of which are substantially rectangular in cross-section and separated b a semi-conducting material. The who e coil is taped in a Well known manner.

I have above explained the principle of my tween said turns under excessive differences of potential between said turns.

, 5. Electrical apparatus for absorbing high frequency energy comprising a coiled conductor and semi-conductingl material in a portion thereof, said semiconducting material being of a character substantially to insulate the turns of said portions from each invention, and' in explaining the best mode other under normal differences of potential end turns and to pass ap reciable current between said end turns un er excessive differences of potential between'said end turns.

7. A high frequency absorber assessing inductance and means distributed) throu h said absorber comprising resistance pa of a character adapted to ass appreciable current between portions o the mductance only under excessive differences of potential between the terminals of the absorber.

8. A reactor adapted to absorb high frequency energy comprising, a coiledconductor having 1ts turns inductively related to one another and a support therefor, said support having semi-conducting material embedding the turns which material is of a character to pass appreciable current between turns only when said conductor is suljected to abnormal differences of potentia 9. Electrical apparatus comprising conducting portions and means for absorbing high frequency energy, sai'd means comprising semi-conducting materlal of such charac.-

ter as to become conducting at abnormallv high differences of potential and disposed bevresistance paths distributed between turns In .hand this 6th dayr of May, 1916. trical energy only whenrsubjected to exces v l tween those rtions which are at different potentials w en the terminals of said appa- 'ratus are maintained at diierent potentials, and means for insulating said absorbing means from ground. A v

10. In a high frequency absorber, the combination with an electrical winding, ofsemiconducting material distributed between and in conductive relation with successive turns thereof, said semi-conducting material being insulated from und and of a character to become conducting only when subject to ab normal differences of potential.

11. In a reactorfor absorbing high frequency energy, the combination with a coiled conductor, of means distributed between turns thereof and of a character to provide for the 'leakage of current between sald turns only when subject to abnormal differences of potential, and means for insulating the first mentioned means from ound.

12. A coiled conductor', an means having thereof of such character as to dissipate elec- .minal of `Said sive potentials, said coiled conductor and means forming a reactor, and means for insulating said reactorfrom ground.

13. Electrical apparatus comprising conductin portions and means for absorbl high quency energy, said means provlild ing leakage paths distributed between such portions and said leakage paths having a negative ampere-volt characteristic and conducting current when the terminals of said apparatusl are maintained at different potentials.

14. An electrical winding and means providing leakage paths having a ne tive ampere-volt characteristic `distribu turns thereof.

4 15. Electrical apparatus comprising a coiled conductor an a semi-conductor having a negative ampere-volt characteristic be tween turns thereof.

16. Electrical apparatus comprising a coiled conductor an semi-conducting material disposed between-turns thereof, the resistance of said semi-conducting material being graded between turns from the termibetween nals of the coiled conductor toward the ceni 17. An-electrical winding comprising a 18. An electrical winding comprising a plurality of coils, the turns of alternate coils being separated from each other by insulating materials and semi-conducting material.

19. A coiled conductor and means distributed between turns thereof `:for dissipating electrical energy, the whole forming a high frequency absorber, said-means being graded in energy dissi ating power from one ter sorber toward the other. 20. A coiled conductorand semi-conduct ing material-disposed betweenv turns thereof forming a reactor, the resistance of said semi-conducting material being graded Abetween turns .from one enti of said coiled conductor toward the other. l 21. A coiled conductor and semi-conducting material distributed throughout the ELMER E. F. CREIGHTON.

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